[bug] multi wan on the fly switching from wan to usb tether broken if using VPN client

Following issue on Brume 2 with fw 4.5.0, if you use openvpn client connection with policy block all non vpn connections, and then plug in a usb tether device so the connection switches to tether, all traffic is blocked, until you manually disable and enable OpenVPN client connection again.

The detection script to check if a interface/connection gets up again is also totally broken and not working properly:

It claims WAN is down, where is is working again. WAN is a cable modem, which sometimes is down for me so I want to use fallback for tether. But the entire fallback algorithm check is buggy and not working as intended.

Restarting router fixes the issue. Or clicking apply under Multi-WAN and then it shows the interface as working again: